As fabrication techniques improve, it is becoming possible to fabricate semiconductor devices with increasingly small dimensions. However, as device dimensions shrink, scaling issues are posing challenges for traditional semiconductor device technology. This has lead to the investigation of alternative materials that can be used to improve performance of semiconductor devices without necessarily depending on the scaling down of devices to improve performance and speed.
A challenge in the investigation of new materials is the slowing down of the development cycle and the learning rate due to traditional processing of an entire substrate that is designed for large scale manufacturing of electronic devices. The processing of the entire substrate can be disadvantageous because the entire substrate is nominally made the same using the same material(s), process(es), and process sequence integration scheme. Conventional full wafer uniform processing results in fewer data per substrate, longer times to accumulate a wide variety of data, and higher costs associated with obtaining such data. Consequently, in order to increase productivity and decrease manufacturing cost there is a need to run more than one processing condition, more than one sequence of processing conditions, more than one process sequence integration flow, and combinations of the same on a single monolithic substrate. This is collectively referred to as “combinatorial process sequence integration.”
A challenge to combinatorial process sequence integration is the traditional manufacturing approach involving lithography and etching to define the device containing the material being screened. In particular, new etching processes may be required for each material being tested. This would slow down development significantly. It is also unknown how the lithography, etching, and polishing used in the traditional approach would affect the materials being screened, thus clouding the results. The testing of new materials also creates the obstacle of having to qualify the necessary processing tools for each of the new materials. Qualification can take several months. New materials also raise concerns of poisoning of a fabrication plant process line and create further challenges for the abatement of the chemical waste created by new chemicals used in processing. Because of these risks to the tools and to the Fab, conventional processes are not practical for high-throughput combinatorial screening.